A calf strain is a tear of the muscle fibres of the muscles at the back of the lower leg and can range from mild to very severe.
Calf injuries usually occur as a result of a sudden pushing off movement or from excessive over-stretching of the calf muscles as demonstrated in jumping activities or during quick changes of direction.

Symptoms
Symptoms of a calf strain can vary significantly but usually involve a sudden sharp pain at the back of the lower leg. The calf muscle will often be tender to touch at the point of injury and swelling and bruising may appear within hours or days.

Depending on how bad the calf injury is, you may be able to continue exercising although you will often have some discomfort / tightness during or after the session. When injuries are more severe you can recall when the injury occurred and or may be unable to walk due to severe pain.
A calf muscle tear is graded from 1 to 3, with grade 3 being the most severe. A grade 1 will not normally need professional treatment whereas grade 2 or 3 injuries, depending on their severity, may require more specialist treatment and rehabilitation advice from a sports injury professional.

Grade 1 symptoms
A Grade 1 calf strain is a minor tear with up to 25% of the muscle fibres affected. You may feel either a twinge of pain in the back of the lower leg or a feeling of “tightness”. You may be able to carry on playing or competing without pain or with only mild discomfort in the calf. However, after exercise finishes there is likely to be “tightness” and/or aching in the calf muscles which can take up to 24 hours to develop.

Grade 2 symptoms
Symptoms of a Grade 2 strain will be more severe than a grade one, with up to 90% of the muscle fibres torn. There will be a sharp pain at the back of the lower leg and usually significant pain on walking afterwards. There is likely to be swelling in the calf muscle with mild to moderate bruising, however this may take hours or days to be visible. On strength testing the muscle, pain will be felt on resisted plantar flexion (pushing the toes and foot downwards towards the floor) against resistance. Tightness and aching may be present in the calf muscle for a week or more before subsiding.

Grade 3 symptoms
Grade 3 injuries involve 90-100% of the muscle fibres and are often referred to as “ruptures”. You will definitely be able to recall exactly when the injury occurred and this will be associated with severe immediate pain at the back of the lower leg. In these situations, the you will be unable to continue/finish exercising and will often be unable to walk due to weakness and pain. This level of injury also presents with considerable bruising and swelling although this may take hours to be visible. On strength testing, the you will be unable to even contract the calf muscle at all and in the case of a full rupture, a gap in the muscle can usually be felt. This is due to a deformity where the muscle is torn and the top part of the muscle may bunch up towards the top of the calf which is clearly visible.
Read more on calf strain assessment and diagnosis.

Self Help Treatment
Apply P.R.I.C.E. (Protection Rest, Ice, Compression, Elevation in the first 48 hrs. Apply a cold therapy and compression wrap as soon as possible to help stop any internal bleeding. Cold therapy can be applied for 10 to 15 minutes every hour initially reducing frequency as pain and swelling goes down. Do not apply ice directly to the skin as it can cause ice burns.
For more comprehensive treatment and to minimise the risk of re-injury, contact a professional physiotherapist who can also devise a full calf strain rehabilitation program including stretching and strengthening exercises and treat the calf strain

Professional Treatment
Electrotherapy such as ultrasound may be applied. This transmits high frequency sound waves into the tissues, which in the early stages can help with pain relief and to reduce swelling. In the later stages of rehabilitation, the ultrasound waves cause a micro massaging effect which can help stimulate blood flow into the muscle.
Sports massage of calf muscles can be applied after the initial acute phase has finished (Warning: do not massage in the first 5 days post injury as this may increase bleeding in the area). The benefits of massage are stimulating blood flow, micro-stretching the muscle and releasing areas of spasm in the muscle. The other major benefit of massage in the latter stages of a calf strain recovery is to encourage optimum of scar tissue and help to align the newly laid fibres in order to encourage effective muscle healing and prevent re-injury
If you seek a sports injury professional’s opinion, he / she will carry out a full assessment of your injury and hopefully make an accurate diagnosis. Then, if required, they will then treat the injury and prescribe and progress a full calf strain rehabilitation program consisting of a number of stretching and strengthening exercises.
Once the initial healing of the muscle has taken place it is essential that the calf muscles are fully strengthened in order to reduce the likelihood that the injury will reoccur or have an adverse effect on future performances.

Anatomy
The calf muscle group consists of two muscles – the Gastrocnemius muscle which is the big muscle at the back of the lower leg and the Soleus muscle which is a smaller muscle lower down in the leg and lies underneath the gastrocnemius.
Gastrocnemius (the larger of the two muscles) originates from the thigh bone (femur) above the knee joint and inserts into the heel bone via the achilles tendon. When the muscle contracts it assists the hamstrings in bending (flexing) the knee but its main function/action is to plantarflex (point toes/foot downwards towards the floor) of the ankle. This is the same movement as standing up onto your tip-toes before you start walking, running or jumping. Gastrocnemius is the powerful muscle of the calf that produces propulsion during dynamic movement such as sprinting and jumping. A medial gastrocnemius muscle injury is often referred to as “Tennis Leg”.
The Soleus muscle originates below the knee joint from the tibia and fibula (shin bones) and also inserts (like gastrocnemius) into to the back of the heel via the Achilles tendon. When the soleus muscle contracts it also plantar flexes the foot, but unlike gastrocnemius has no effect on bending the knee. If the soleus muscle is damaged as opposed to the gastrocnemius, the pain is usually lower down the leg but is not painful when attempting to bend the knee (unlike gastrocnemius). The soleus muscle is the main calf muscle that fascilitates running for long periods (endurance activities).
Either of these two muscles can be injured but the usually the injury occurs at the junction where the muscle meets the Achilles tendon called the “musculotendinous junction”.

Calf Muscle Injury Prevention
There are particularly common in racket sports such as tennis or badminton which involve repeated jumping and changes of direction. Runners also suffer calf injuries and they are common in both explosive sprinting events as well as long distance (endurance) events.
Shortened muscles are also susceptible to injury and this is most commonly seen in women who wear high heels a lot of the time. Over a period of time the calf muscles adapt and shorten due to the excessively raised heel and then when running shoes or flat shoes are worn, the calf muscles are stretched excessively and are at more risk of injury. Another linked factor in calf injuries is that wearing high heels can weaken the calf muscles thereby also increasing the risk of injury.